Thermic telephone.



0. FISCHER. l HERMlc TELEPHONE.

A PPucAnon'ryLEp MAR. 19. 191g'. Y Patented Mar. 7,1916.

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@WM I l 0. FISCHER. THEHMlc TELEPHONE.

i APPLICATIN4 FILED MAR. I9. |914.

, Patented Mar. 7,1916.

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, W www W V frz/whim' Ww Fisc/kr OTTO FISCHER,

UNTTED STATES BATENT FFTCE. y

0F UTRECHT, NETHERLANDS, ASSIGNOB. TO NAAMLOZE VENNOOT- SCHAP DENEDERLANDSGHE THERMO-TELEPI-IOO'N MAATSCHAPPIJ, lOE UTRECHT,NETHERLANDS, A CORPORATION OF THE NETHERLANDS. 1

THERMIG TELEPHONE.

Specicaton of Letters Patent.

Patented Mai, a, raie'.

Application filed March 19, 1914,. Serial No. 825,934.

To all whom it may concern .f

Be it known that I, OTTO FISCHER, a subject of the German Emperor, and aresident of Utrecht, Netherlands, have invented certain new and usefulImprovements in Thermic Telephones, of which the following is aspecification. My invention relates to thermic telephones, andparticularly to the' heat-conductors thereof and to the carriers of suchconductors. Heat-'conductors of this character have been made heretoforefrom wires (say platinum wires) coated according to Wollastones methodand formed into the shape of loops, the bend of the loop being thendipped into acid to a depth corresponding to that of the receiver, andthus freed of the coating on the dipped portion. Tnjthe usual practice,'the Wollastone wire, after being bent into loop-form, is provided witha cast or block-like inclosing body made of acidproof insulatingmaterial, only that portion of the wire which is to be treated withacidl being allowed to project from the said block or carrier. In theoperation of this process, considerable difficulties have beenexperienced owing to the fact the exceedingly line wire loop projectingfrom the carrier or cast was bent sidewise, when lifted from the acidbath, by the amount of acid adhering to said carrier, so that 'it becamenecessary to bend the loop back to its proper position, and thisrighting of the fine loop frequently caused it to become injured.

According to my invention, this defect is avoided by providing the loopswhich are to be treated with acid, ywith holders at their free ends, andconnecting these Wollastone wires with a carrier, and, suspended fromthis carrier, the wires are dipped in the acid bath to the` desiredextent. When a heat' conductor of this character is lifted from the acidbath, the acid will run off readily from the Wire loops, and thesound-prodiing,

very sensitive wire loops will not be deformed.`

The free ends of the wire loops may be detachably fastened directly inclosely set v holes of a holder which at the same time forms a carriercommon toall the wires.

This arrangement permits of simplifying` greatly the construction of aheat conductor composed of a large number of wire loops,

without the use of a body cast around a portion of the wires. Theseholders common to all the wires are readily accessible and serve notonly to carry the wires during the dipping operation, but in thetelephone casing as well.

It is well-known that combining a plurality of wire loops to form avsingle heat conductor, materially increases the acoustic effect ofthetherluic telephone containing such heat conductor. Thermic telephones,however, are made of very small dimensions, their receivers beingadapted to be fitted against the auditory meatus directly; on account ofthese small dimensions, considerable practical diiiiculties areexperienced Y 'struction the wire loops were connected with each otherpermanently, the entire heat conductor body became unserviceable in caseeven one of the very delicate wire loops was injured either during thedipping process or during the subsequent use of the heat conductor, andthis was a serious drawback of said older construction.

It is a further object of my invention to avoid the defect just noted,that is to say, to provlde a carrier fora thermic conductorl which willallow a very large number of 'wire loops to be placed within a smallspace,

whilerin the event of injury to one or more of the loops, the damagedloop can be removed separately in a convenient manner, withoutdisturbing the .other wire loops; In order to accomplish this result, Temploy, as

a carrier for the thermi-c conductor, a ringshaped` holder in which theradially arranged wire loops are set removably. This not only simplifiesthe construction of the heat conductor, but facilitates theacidtreatment of the several wire loops arranged in groups. v

Reference is to be' had to the accompany'- ing drawings, in which-vFigure l 1s an elevation, vpartly in sec-- tion, of one form of thermicconductor niade consisting of a plurality or" wire loops mounted oncarriers Fig. 4 is an anial section of a telephone receiver containing athermic conductor of the construction shown l in'Fig. 3; Fig. 5 is aside elevation, with parts in section, and Fig. 6 a front elevation,with parts 1n section, of another form of thermic conductor 'madeaccording to lao my invention; Figs. 7 and S are ,respecltively a sideelevation vand a. front eleva.- tion, each with parts in section,yshowing still another form of heat conductor accord- 'ing to myinvention; Fig. 9 is a longitudinal section through a telephonevcontaining a heat conductor of the character shown in Figs. 5 and 6;Fig( 1()v is a vertical section, taken on lineA--B of Fig. 11, showingan annularcarrier for the heatconductor; Fig. 11 is a bottom view of thearrangement shown in Fig. 10, with some of the wire loops omitted; Fig.12 is a vertical section through a thermic telephone intended forpersons hard of hearing, said telephone re- -fceiver containing Wireloops and a carrier of the construction shown in Figs. 10 and 1'1; andFigs. 13 and 14 are respectively a side elevation with parts in section,and an end view illustrating a special process for the manufacture of anannular carrier of the kind embodied in Figs. 10, 11 and 12.

All the figures of the drawing show the i parts larger than naturalsize.

"In the construction illustrated by Figs. 1 and 2, the loop-shapedl/Vollastone wire 1 is passed at each end 2, 3 through a holder 4, 5respectivelymade of electrically conducting material7 with which saidWire endsl areconnected in any suitable inanner, as by soldering orriveting. The holders 4, 5 are provided with-holes 6, 7 respectively.The thermic conductor formed in this way is, while hanging freely in theposition shown, dipped in an acid bath to the desired depth, asindicated bythe dotted horizontal line in Fig. 1, so that the dippedportion 8 of ythe loop is freed of its coating, thus exposing theplatinum co-re, in the usual manner of treating VVollastone wires. i

In Fig. 3 I haveshown a thermic conduc- 'tor comprising a plurality ofwire loops,

and in this case the wire loops 1, before dipping them into the acidbath, are secured to holders. 45 in the saine manner as described above,and thenstrungc-n carriers .9 and 10 respectively which pass through theholes 6, 7 respectively. rIhe number of wire loops in each group dependson the strength or aggregate cross section it is desii-ed to give to thethermic conductor. For the purpose of .connecting'the wire loops withthe circuit, the carriers 9 and 1'0 are provided or connected with rods1,1, 12 respectively adapted to receive snap-on connectors of awell-known character.

Theinounting of the thermic conductor is preferably carried out in themanner' shown in Fig. 4. rlfhe connector members 11, 12 are embedded ina block 13 of insiilating material, which is surrounded by ,a casing orshell 15, the open end of which may be closed by a cover 14 .havingapertures 16 for the passage of the sound.

It will be seen that each wire loop 1, with the small holders 4, 5 atits ends, is removable readily froin the carriers 9, 10 on which thewire loops with their attached holders are strung; these. loops maytherefore be re-y moved and replaced with the greatest ease.

In the construction illustrated by Figs. 5'

to 9 inclusive, the holders 9, 10a form coin*- mon carriers foi' therespectiveiends of all the wire loops 1 and at the same timeconstitute'T-shaped bodies in conjunction -With the connector rods orpins 11,'12f1'espectively. These carriers are provided either withclosely set holes (Figs' 5 and`6) or with slits (Figs. 7 and 8) for thereception of the ends or' the wire loops 1, said ends being preferablyflattened, in the construction' shown in Figs. 7 and 8, as indicated at17, 18, and being inserted in the slits either laterally or from below.The construction of the thermic conductors is greatly simplilied in thismanner, since the free ends of the wire loops 1 are inserted directly inthe holders 9, 10a forming carriers for said wires, and if requiredhthewire ends may be secured say by soldering or riveting. The cross sectionor' the holders 9a, 10d may be varied, thus in Figs. 5 and 6 a. circularcross section is shown, while in Figs. 7 and 8 the holders are of?rectangular cross section, The length of theholders 9, 10L of coursedepends on thelnumber of wire loops to be used, and this again dependson the desired strength or aggregate cross section of the thermicconductor. Here too, the several wire loops 1 are detachableindividually from the carriers 9a, 10a on which they are strung.

The complete receiver containing a thermic conductor of the constructionshown in Figs. 7 and 8 is illustrated in Fig. 9, and

. has the connector rods or pins 11, 12 emy10 and 11 consists of aring-shaped holder comprising an inner metal ring 19, an outer metalring 20, and an insulating ring 21 interposed between them. On theirlower faces, the metal rings 19, 20 are provided with radial openings22, 23 respectively, which in the particular form illustrated are madeas slits or notches. lThe (preferably flattened) free ends '24 of thewire loops 1 are inserted detachably in saidopenings.`

The annular holder 19, 20, 21 connects the wire loops 1 to formanannular lgrpup, vand this holder, .with the loops hanging down from itfreely, is moved downward until the lower portions of the wire loops aredipped to the desired extent in the acid bath to remove the coating ofthe wires in the wellknown manner. It will be seen that theacid-treatment is carried out without requiring a cast connecting theseveral wire loops, andthus I am enabled not only to regulate the depthof dipping accurately and easily, but to dip the wires to a considerablygreater depth than with'the method used hitherto, since the height ofthe vholder' 19, 20, v21 is much smaller than that of the cast employedhitherto.

If during the acid treatment one or more wire'loops 1 shouldbe damaged,they can be readily removed, individually, by simply pulling them out ofthe metal rings 19, 20, whereupon sound, previously dipped wire loopswill be substituted for thedamaged ones.

For the purpose of making the necessary electrical connections, themetal rings 19, 20 are provided or connected with rods or pins v2, 26respectively adapted to 'receive snapon connections of the well-knowncharacter, as indicated at 27, 28 in Fig. 12, the sleeves 27, 28 fittingover the elastic (split) ends of the rods 25, 26 respectively, andserving also to hold the rings 19, 20, 21. 4These sleeves 27. 28 arescrewed into openings of an insulating block 29, fitted into. a shell orcasing 30, the upper end of which has a central opening 33 for thepassage of the connecting wires 31, 32 secured to the sleeves 27 28respectively. On the casing 30 is screwed a sleeve 34, preferablypear-shaped and provided with a sound opening 35. The interior shoulder36 of the sleeve 34 presses against the protecting cover 37 whichsurrounds the wire loops, and thus the said cover is held against theblock 29. At its lower end, the cover 37' is provided with apertures 38vregistering with the sound opening 35.

lVith a heat conductor carrier of the construction described above, itis very easy to remove from the thermic telephone, any wire loop l whichmay have become defective, without disturbing the other loops. All thatis necessary to effect this, is to unscrew the sleeve 34. pull off thecover 37 with the connector rods 25, 2G from the sleeves 27, 28. andremove the defective wire or wires '1 from its or their sockets in themetal rings 19, 20d; new wire loops are then inserted, and the parts puttogether as before.

The annular holders forming the carrier for the heat conductor' arepreferably manufactured, in the manner illustrated by Figs. 13 and lil.According to this process of manufacture, two metal tubes 39, 40 and aninterposed tube 41 of insulating material are put togethertelescopically, as shown. From the composite tube thus formed, annularsections are cut oit, as indicated by the vertical dotted lines in Fig.13. By means of ,a milling cutter, these annular bodies are thenprovided, on one of their end faces, with the radial cuts or slits forreceiving the ends of the wire loops. This method allows me tomanufacture the annular heat conductor carriers very accurately,notwithstanding their small dimensions, and in an economical mannersuited for production on a large scale.

Various modifications may be made without departing from the natu-re of.my invention as set forth in the appended claims.

I claim:

1. In a thermic telephone, aseries of wire loops, and a carrier withwhich the individual loops are connected detachably.

2. A heat conductor carrier for thermic telephones, comprising anannular member adapted to form a part of the telephone and consistingofan inner metal ring, an outer metal ring, and a .ring of insulatingmaterial interposed between said metal rings, the latter two rings beingprovided with radial openings for the removable insertion ofthe freeends of the thermic wire loops.

3. A thermic telephone comprising a casing, a carrier set therein andconsisting of two annular conducting members insulatedfrom each otherand provided with openings, and wire loops the ends of which `aresecured to the respective conducting members at the openings thereof.

4. A thermic telephone comprising a casing, a carrier set therein andconsisting of two conducting rings of different diameters and a ring ofinsulating material interposed between said conducting rings, the latterbeing'provided with openings, and wire loops the ends of which aresecured removably in the openings of. the respective conducting rings.

In testimony whereof, I have signed this specification in the presenceof two subscribing witnesses.

- OTTO FISCHER.

Copies of this patent may be obtained for ve cents each, by addressingthe Commissioner c? Patents Washington, D. C. f

